New technique for submillimeter-wave reflector construction

Several submillimeterwave astronomical telescope projects have recently employed the use of cast aluminum, machined panels for the reflector surface. Although the resulting surface has several advantages, there are also some drawbacks. In particular, the weight per area is relatively high since it is difficult to make elaborate casting details in the backing ribs and there are quality control concerns in the casting process. To address these problems, we have developed an alternate method of forming the metal reflector blank prior to machining. We have used a high grade, proprietary cast aluminum sheet to form over a mold by slumping. Light- weightedbacking ribs are then welded to the rear. The particular application discussed here is a complete 1.5 m submillimeter wave reflector. The technique is of interest for smaller size panels typically used with large, submillimeter wavelength reflectors.